Hydroelectric Energy

Generating clean energy for vital services

The Hetch Hetchy Power system is composed of three hydroelectric powerhouses: Moccasin Powerhouse, which includes a small, in-line hydroelectric unit, Kirkwood Powerhouse and Holm Powerhouse. The combined total hydroelectric output for these facilities is over 400 megawatts. Hydroelectric generation at Moccasin and Kirkwood Powerhouses rely on gravity-driven water flowing downhill from the Hetch Hetchy Reservoir. Holm Powerhouse generates energy from gravity-driven water flowing downhill from Cherry Lake. On average, the Hetch Hetchy Power System generates 1.6 billion kilowatt hours of clean, hydroelectric energy each year.

This process starts at the source. Gravity gently coaxes water from the reservoirs in the Hetch Hetchy Water and Power System. At our hydroelectric powerhouses, large turbines harness the kinetic energy of gravity-driven water, transforming it into hydroelectric power. This clean energy is then transmitted to San Francisco along City-owned transmission lines that transverse the State of California from east to west. Once in the City, the energy is distributed to the City’s municipal facilities and retail customers; SFO, SFGH, MUNI, Police, Fire, retail City tenants, residences and businesses in the San Francisco Shipyard and Treasure Island. In normal-to-high precipitations years, we sell energy on the California energy markets.

Moccasin Power House

Hetch Hetchy Reservoir- O'Shaughnessy Dam

Moccasin Power House, featured above, is the powerhouse furthest downstream. The control room at Moccasin Powerhouse not only operates all three powerhouses, but also remotely starts and stops generating units, adjusts generator speeds and takes all necessary readings. Holm Powerhouse is the largest of the three powerhouses.

San Francisco benefits immensely from owning and operating the Hetchy Power System. Hetch Hetchy hydroelectric energy is cost-effective and 100% greenhouse gas-free. It does not produce any harmful radioactive byproducts or leave behind any waste. Its cost-effective, clean electricity keeps our environment clean and helps the City’s fiscal bottom-line.